1. Field of the Invention
This invention relates to a wire feeding device for a bulk material baler, and more particularly to a device for feeding wires individually selected from a plurality of wires.
2. Related Art
Wire baling of bulk materials benefits from increased speed and reduced materials cost through automation. Bulk materials include fibrous bulk materials such as cotton and nylon. Fibrous materials are commonly formed into bales by simultaneous compression and binding. There is a continuing need in the automated baling art to improve the efficiency, reliability and accuracy of the bale binding process.
Baling wire performance requirements vary depending upon the bulk material being baled. Such requirements range from industry standard specifications to general operational parameters, such as minimum speeds required for profitability. The Cotton Council issues standard baling constraints specifying particular ranges for the length of wire around the bale and the tension that the wire must withstand.
Current automated baling machines use an articulated track to guide wire around bales of bulk material, while that bale is under compression. Part of the wire guide track in current automated balers must be removable to a second position after the ends of the baling wire have been tied together, in order to allow ejection of the bale and insertion into the baler of the next unit of material for baling. Material to be baled is typically introduced into the automatic baler under vertical compression. Typical pressures for an industry standard 500 pound, 20 by 54 inch bale are in excess of 300 tons. Horizontal plates called follower blocks apply compression through platens which contact the surface of the cotton or other material being compressed. The platens incorporate slots which run laterally to the longitudinal axis of the bale. The Industry Standard number of binding wires for cotton bales is six. Accordingly, there are six slots in the platens. These allow the baling wire to be wrapped around the bale while it is still under compression. The lateral slots have lateral channels behind them for insertion of wire guide tracks in both the upper and lower platens in automatic balers.
It is not uncommon for a wire being looped around the bulk material to bind up in the track or otherwise misfeed. In this case, it is necessary to remove the bound up wire and retie the bale. Presently, there exists no easy or convenient method to re-feed the wire around the bale. Either the wire can be looped manually which presents some hazard to the operator or alternatively the tied wires may be cut and the process begun again. There remains a need for an automatic baling apparatus that can correct mis-feeding errors.
Moreover, in order to loop baling wire around bulk material to be baled, release it from a guide track and knot the ends, tension must be generated in the wire. Likewise, in order to properly knot the ends of the wire, tension must be maintained in the twisting procedure that generates the knot. These tensions must be maintained within prescribed ranges to optimize efficiency and to produce a final bale compliant with industry standards.
Typically, tension is created in the wire by reversing the wire feed mechanism. In other words, the wire feed mechanism reverses, pulling the wire out of the track and drawing it tight against the bail. In the case of a misfeed, it is necessary to not only loop a single wire around the bale, but it is also necessary to tension the wire. There remains a need in the art for a simple but effective apparatus for feeding and tensioning a single wire loop.
U.S. Pat. No. 3,119,536 issued to Berkeley on Jan. 28, 1964 discloses a wire feeding apparatus. The device includes a constantly rotating shaft, a first gear connected to the rotating shaft, and a second gear which is selectively engaged with the first gear. The second gear is mounted on a square bar and is biased upwardly away from the first rotating gear. The Berkeley device uses pivot arms that push the second gear downwardly to overcome the bias and engage with the first gear such that wire is fed. The Berkeley device is relatively complex and expensive due to the number of components it requires. Moreover, the Berkeley device is inefficient in that it utilizes a constantly rotating shaft.
Other prior art devices achieve selective drive of separate wire feed devices by separately powering each of three or more wire feed devices with an individually dedicated servo motor. While this achieves selective engagement of individual wire feeders, it clearly multiplies the expense by using multiple servo motors. There is a need in the art for a device with selective engagability capabilities that is less expensive.
There remains a need in the art for an economical wire feeding apparatus for feeding and tensioning wire that is simple, reliable and inexpensive.